The phenomenal growth in the demand for wireless communications has put persistent pressure on wireless network operators to improve the capacity of their communication networks. To improve the spectral efficiency of these networks, scarce radio resources have to be reused aggressively in neighboring cells. As a result, inter-cell interference has become a main source of signal disturbance, limiting not only the service quality to users at the cell edges, but also the overall system throughput.
Coordinated multipoint (CoMP) reception in the uplink is one technique being considered for mitigating inter-cell interference in IMT-Advanced systems. CoMP reception differs from reception in a conventional system in that uplink signals are received at multiple antennas deployed across several adjacent cell sites (i.e., radio access points), and then transported to a common location for joint processing. In effect, this architecture forms a “super-cell,” called a CoMP cell, where uplink signals that would have been treated by a conventional cell as inter-cell interference are instead treated by the CoMP cell as desired signals. The mitigation in inter-cell interference is expected to significantly improve system performance, especially for users near the edge of a conventional cell.
Joint processing of the received uplink signals, however, requires significant and potentially prohibitive computational complexity. Multi-antenna Generalized RAKE receivers, for example, are particularly well suited for joint processing in CoMP cells of High Speed Packet Access (HSPA) systems, given their ability to suppress other-user interference. Yet the computational complexity of multi-antenna G-RAKE receivers grows with the number of antennas used for CoMP reception, as well as with the number of fingers allocated to each antenna. As CoMP reception is most effective with a large number of antennas and with a large number of fingers allocated to each antenna, computational complexity is a significant limiting factor in the performance of CoMP reception.